/* 
 * Copyright 2010 Real Cloud. All rights reserved.
 * Real Cloud PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 * 
 * @AsyncTask.java - 2013-1-31 - Administrator
 */

package com.goldplusgold.support.lib.widget;

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


import android.os.Handler;
import android.os.Message;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.FutureTask;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * <p>AsyncTask enables proper and easy use of the UI thread. This class allows to perform
 * background operations and publish results on the UI thread without having to manipulate threads
 * and/or handlers.</p>
 *
 * <p>AsyncTask is designed to be a helper class around {@link Thread} and {@link Handler} and does
 * not constitute a generic threading framework. AsyncTasks should ideally be used for short
 * operations (a few seconds at the most.) If you need to keep threads running for long periods of
 * time, it is highly recommended you use the various APIs provided by the
 * <code>java.util.concurrent</code> pacakge such as {@link Executor}, {@link ThreadPoolExecutor}
 * and {@link FutureTask}.</p>
 *
 * <p>An asynchronous task is defined by a computation that runs on a background thread and whose
 * result is published on the UI thread. An asynchronous task is defined by 3 generic types, called
 * <code>Params</code>, <code>Progress</code> and <code>Result</code>, and 4 steps, called
 * <code>onPreExecute</code>, <code>doInBackground</code>, <code>onProgressUpdate</code> and
 * <code>onPostExecute</code>.</p>
 *
 * <div class="special reference"> <h3>Developer Guides</h3> <p>For more information about using
 * tasks and threads, read the <a href="{@docRoot}guide/topics/fundamentals/processes-and-threads.html">Processes
 * and Threads</a> developer guide.</p> </div>
 *
 * <h2>Usage</h2> <p>AsyncTask must be subclassed to be used. The subclass will override at least
 * one method ({@link #doInBackground}), and most often will override a second one ({@link
 * #onPostExecute}.)</p>
 *
 * <p>Here is an example of subclassing:</p> <pre class="prettyprint"> private class
 * DownloadFilesTask extends AsyncTask&lt;URL, Integer, Long&gt; { protected Long
 * doInBackground(URL... urls) { int count = urls.length; long totalSize = 0; for (int i = 0; i <
 * count; i++) { totalSize += Downloader.downloadFile(urls[i]); publishProgress((int) ((i / (float)
 * count) * 100)); // Escape early if cancelAll() is called if (isCancelled()) break; } return
 * totalSize; }
 *
 * protected void onProgressUpdate(Integer... progress) { setProgressPercent(progress[0]); }
 *
 * protected void onPostExecute(Long result) { showDialog("Downloaded " + result + " bytes"); } }
 * </pre>
 *
 * <p>Once created, a task is executed very simply:</p> <pre class="prettyprint"> new
 * DownloadFilesTask().execute(url1, url2, url3); </pre>
 *
 * <h2>AsyncTask's generic types</h2> <p>The three types used by an asynchronous task are the
 * following:</p> <ol> <li><code>Params</code>, the type of the parameters sent to the task upon
 * execution.</li> <li><code>Progress</code>, the type of the progress units published during the
 * background computation.</li> <li><code>Result</code>, the type of the result of the background
 * computation.</li> </ol> <p>Not all types are always used by an asynchronous task. To mark a type
 * as unused, simply use the type {@link Void}:</p> <pre> private class MyTask extends
 * AsyncTask&lt;Void, Void, Void&gt; { ... } </pre>
 *
 * <h2>The 4 steps</h2> <p>When an asynchronous task is executed, the task goes through 4
 * steps:</p>
 * <ol> <li>{@link #onPreExecute()}, invoked on the UI thread before the task is executed. This
 * step
 * is normally used to setup the task, for instance by showing a progress bar in the user
 * interface.</li> <li>{@link #doInBackground}, invoked on the background thread immediately after
 * {@link #onPreExecute()} finishes executing. This step is used to perform background computation
 * that can take a long time. The parameters of the asynchronous task are passed to this step. The
 * result of the computation must be returned by this step and will be passed back to the last
 * step.
 * This step can also use {@link #publishProgress} to publish one or more units of progress. These
 * values are published on the UI thread, in the {@link #onProgressUpdate} step.</li> <li>{@link
 * #onProgressUpdate}, invoked on the UI thread after a call to {@link #publishProgress}. The
 * timing
 * of the execution is undefined. This method is used to display any form of progress in the user
 * interface while the background computation is still executing. For instance, it can be used to
 * animate a progress bar or show logs in a text field.</li> <li>{@link #onPostExecute}, invoked on
 * the UI thread after the background computation finishes. The result of the background
 * computation
 * is passed to this step as a parameter.</li> </ol>
 *
 * <h2>Cancelling a task</h2> <p>A task can be cancelled at any time by invoking {@link
 * #cancel(boolean)}. Invoking this method will cause subsequent calls to {@link #isCancelled()} to
 * return true. After invoking this method, {@link #onCancelled(Object)}, instead of {@link
 * #onPostExecute(Object)} will be invoked after {@link #doInBackground(Object[])} returns. To
 * ensure that a task is cancelled as quickly as possible, you should always check the return value
 * of {@link #isCancelled()} periodically from {@link #doInBackground(Object[])}, if possible
 * (inside a loop for instance.)</p>
 *
 * <h2>Threading rules</h2> <p>There are a few threading rules that must be followed for this class
 * to work properly:</p> <ul> <li>The AsyncTask class must be loaded on the UI thread. This is done
 * automatically as of {@link android.os.Build.VERSION_CODES#JELLY_BEAN}.</li> <li>The task
 * instance
 * must be created on the UI thread.</li> <li>{@link #execute} must be invoked on the UI
 * thread.</li> <li>Do not call {@link #onPreExecute()}, {@link #onPostExecute}, {@link
 * #doInBackground}, {@link #onProgressUpdate} manually.</li> <li>The task can be executed only
 * once
 * (an exception will be thrown if a second execution is attempted.)</li> </ul>
 *
 * <h2>Memory observability</h2> <p>AsyncTask guarantees that all callback calls are synchronized
 * in
 * such a way that the following operations are safe without explicit synchronizations.</p> <ul>
 * <li>Set member fields in the constructor or {@link #onPreExecute}, and refer to them in {@link
 * #doInBackground}. <li>Set member fields in {@link #doInBackground}, and refer to them in {@link
 * #onProgressUpdate} and {@link #onPostExecute}. </ul>
 *
 * <h2>Order of execution</h2> <p>When first introduced, AsyncTasks were executed serially on a
 * single background thread. Starting with {@link android.os.Build.VERSION_CODES#DONUT}, this was
 * changed to a pool of threads allowing multiple tasks to operate in parallel. Starting with
 * {@link
 * android.os.Build.VERSION_CODES#HONEYCOMB}, tasks are executed on a single thread to avoid common
 * application errors caused by parallel execution.</p> <p>If you truly want parallel execution,
 * you
 * can invoke {@link #executeOnExecutor(java.util.concurrent.Executor, Object[])} with {@link
 * #THREAD_POOL_EXECUTOR}.</p>
 */
public abstract class AsyncTask<Params, Progress, Result> {
    public static final int TYPE_LOCAL = 1;
    public static final int TYPE_NET = 2;
    private static final String LOG_TAG = "AsyncTask";
    private static final int CORE_POOL_SIZE = 4;
    private static final int MAXIMUM_POOL_SIZE = 128;
    private static final int KEEP_ALIVE = 1;
    private static final ThreadFactory sThreadFactory = new ThreadFactory() {
        private final AtomicInteger mCount = new AtomicInteger(1);

        public Thread newThread(Runnable r) {
            return new Thread(r, "AsyncTask #" + mCount.getAndIncrement());
        }
    };

    private static final BlockingQueue<Runnable> sPoolWorkQueue =
            new LinkedBlockingQueue<Runnable>(20);
    /**
     * An {@link Executor} that can be used to execute tasks in parallel.
     */
    public static final Executor THREAD_POOL_EXECUTOR
            = new ThreadPoolExecutor(CORE_POOL_SIZE, MAXIMUM_POOL_SIZE, KEEP_ALIVE,
            TimeUnit.SECONDS, sPoolWorkQueue, sThreadFactory, new ThreadPoolExecutor.DiscardOldestPolicy());
    private static final ThreadFactory sThreadFactoryLocal = new ThreadFactory() {
        private final AtomicInteger mCount = new AtomicInteger(1);

        public Thread newThread(Runnable r) {
            return new Thread(r, "AsyncTask #" + mCount.getAndIncrement());
        }
    };
    private static final BlockingQueue<Runnable> sPoolWorkQueueLocal =
            new LinkedBlockingQueue<Runnable>(20);
    public static final Executor THREAD_POOL_EXECUTOR_LOCAL =
            new ThreadPoolExecutor(CORE_POOL_SIZE, MAXIMUM_POOL_SIZE, KEEP_ALIVE,
                    TimeUnit.SECONDS, sPoolWorkQueueLocal, sThreadFactoryLocal, new ThreadPoolExecutor.DiscardOldestPolicy());


    /**
     * An {@link Executor} that executes tasks one at a time in serial order.  This serialization
     * is
     * global to a particular process.
     */
//    public static final Executor SERIAL_EXECUTOR = new SerialExecutor();

    private static final int MESSAGE_POST_RESULT = 0x1;
    private static final int MESSAGE_POST_PROGRESS = 0x2;

    private static final InternalHandler sHandler = new InternalHandler();

    //    private static volatile Executor sDefaultExecutor = SERIAL_EXECUTOR;
    private final WorkerRunnable<Params, Result> mWorker;
    private final FutureTask<Result> mFuture;
    private final AtomicBoolean mCancelled = new AtomicBoolean();
    private final AtomicBoolean mTaskInvoked = new AtomicBoolean();
    private volatile Status mStatus = Status.PENDING;

//    private static class SerialExecutor implements Executor {
//        final ArrayDeque<Runnable> mTasks = new ArrayDeque<Runnable>();
//        Runnable mActive;
//
//        public synchronized void execute(final Runnable r) {
//            mTasks.offer(new Runnable() {
//                public void run() {
//                    try {
//                        r.run();
//                    } finally {
//                        scheduleNext();
//                    }
//                }
//            });
//            if (mActive == null) {
//                scheduleNext();
//            }
//        }
//
//        protected synchronized void scheduleNext() {
//            if ((mActive = mTasks.poll()) != null) {
//                THREAD_POOL_EXECUTOR.execute(mActive);
//            }
//        }
//    }

    /**
     * Creates a new asynchronous task. This constructor must be invoked on the UI thread.
     */
    public AsyncTask() {
        mWorker = new WorkerRunnable<Params, Result>() {
            public Result call() throws Exception {
                mTaskInvoked.set(true);

                android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_DEFAULT);
                //noinspection unchecked
                return postResult(doInBackground(mParams));
            }
        };

        mFuture = new FutureTask<Result>(mWorker) {
            @Override
            protected void done() {
                try {
                    postResultIfNotInvoked(get());
                } catch (InterruptedException e) {
                    android.util.Log.w(LOG_TAG, e);
                } catch (ExecutionException e) {
                    throw new RuntimeException("An error occured while executing doInBackground()",
                            e.getCause());
                } catch (CancellationException e) {
                    postResultIfNotInvoked(null);
                }
            }
        };
    }

    /**
     * @hide Used to force static handler to be created.
     */
    public static void init() {
        sHandler.getLooper();
    }

//    public static void setDefaultExecutor(Executor exec) {
//        sDefaultExecutor = exec;
//    }

    private void postResultIfNotInvoked(Result result) {
        final boolean wasTaskInvoked = mTaskInvoked.get();
        if (!wasTaskInvoked) {
            postResult(result);
        }
    }

    private Result postResult(Result result) {
        @SuppressWarnings("unchecked")
        Message message = sHandler.obtainMessage(MESSAGE_POST_RESULT,
                new AsyncTaskResult<Result>(this, result));
        message.sendToTarget();
        return result;
    }

    /**
     * Returns the current status of this task.
     *
     * @return The current status.
     */
    public final Status getStatus() {
        return mStatus;
    }

    /**
     * Override this method to perform a computation on a background thread. The specified
     * parameters
     * are the parameters passed to {@link #execute} by the caller of this task.
     *
     * This method can call {@link #publishProgress} to publish updates on the UI thread.
     *
     * @param params The parameters of the task.
     * @return A result, defined by the subclass of this task.
     * @see #onPreExecute()
     * @see #onPostExecute
     * @see #publishProgress
     */
    protected abstract Result doInBackground(Params... params);

    /**
     * Runs on the UI thread before {@link #doInBackground}.
     *
     * @see #onPostExecute
     * @see #doInBackground
     */
    protected void onPreExecute() {
    }

    /**
     * <p>Runs on the UI thread after {@link #doInBackground}. The specified result is the value
     * returned by {@link #doInBackground}.</p>
     *
     * <p>This method won't be invoked if the task was cancelled.</p>
     *
     * @param result The result of the operation computed by {@link #doInBackground}.
     * @see #onPreExecute
     * @see #doInBackground
     * @see #onCancelled(Object)
     */
    protected void onPostExecute(Result result) {
    }

    /**
     * Runs on the UI thread after {@link #publishProgress} is invoked. The specified values are
     * the
     * values passed to {@link #publishProgress}.
     *
     * @param values The values indicating progress.
     * @see #publishProgress
     * @see #doInBackground
     */
    protected void onProgressUpdate(Progress... values) {
    }

    /**
     * <p>Runs on the UI thread after {@link #cancel(boolean)} is invoked and {@link
     * #doInBackground(Object[])} has finished.</p>
     *
     * <p>The default implementation simply invokes {@link #onCancelled()} and ignores the result.
     * If
     * you write your own implementation, do not call <code>super.onCancelled(result)</code>.</p>
     *
     * @param result The result, if any, computed in {@link #doInBackground(Object[])}, can be null
     * @see #cancel(boolean)
     * @see #isCancelled()
     */
    protected void onCancelled(Result result) {
        onCancelled();
    }

    /**
     * <p>Applications should preferably override {@link #onCancelled(Object)}. This method is
     * invoked
     * by the default implementation of {@link #onCancelled(Object)}.</p>
     *
     * <p>Runs on the UI thread after {@link #cancel(boolean)} is invoked and {@link
     * #doInBackground(Object[])} has finished.</p>
     *
     * @see #onCancelled(Object)
     * @see #cancel(boolean)
     * @see #isCancelled()
     */
    protected void onCancelled() {
    }

    /**
     * Returns <tt>true</tt> if this task was cancelled before it completed normally. If you are
     * calling {@link #cancel(boolean)} on the task, the value returned by this method should be
     * checked periodically from {@link #doInBackground(Object[])} to end the task as soon as
     * possible.
     *
     * @return <tt>true</tt> if task was cancelled before it completed
     * @see #cancel(boolean)
     */
    public final boolean isCancelled() {
        return mCancelled.get();
    }

    /**
     * <p>Attempts to cancelAll execution of this task.  This attempt will fail if the task has
     * already
     * completed, already been cancelled, or could not be cancelled for some other reason. If
     * successful, and this task has not started when <tt>cancelAll</tt> is called, this task should
     * never run. If the task has already started, then the <tt>mayInterruptIfRunning</tt>
     * parameter
     * determines whether the thread executing this task should be interrupted in an attempt to
     * stop
     * the task.</p>
     *
     * <p>Calling this method will result in {@link #onCancelled(Object)} being invoked on the UI
     * thread after {@link #doInBackground(Object[])} returns. Calling this method guarantees that
     * {@link #onPostExecute(Object)} is never invoked. After invoking this method, you should
     * check
     * the value returned by {@link #isCancelled()} periodically from {@link
     * #doInBackground(Object[])} to finish the task as early as possible.</p>
     *
     * @param mayInterruptIfRunning <tt>true</tt> if the thread executing this task should be
     *                              interrupted; otherwise, in-progress tasks are allowed to
     *                              complete.
     * @return <tt>false</tt> if the task could not be cancelled, typically because it has already
     * completed normally; <tt>true</tt> otherwise
     * @see #isCancelled()
     * @see #onCancelled(Object)
     */
    public final boolean cancel(boolean mayInterruptIfRunning) {
        mCancelled.set(true);
        return mFuture.cancel(mayInterruptIfRunning);
    }

    /**
     * Waits if necessary for the computation to complete, and then retrieves its result.
     *
     * @return The computed result.
     * @throws CancellationException If the computation was cancelled.
     * @throws ExecutionException    If the computation threw an exception.
     * @throws InterruptedException  If the current thread was interrupted while waiting.
     */
    public final Result get() throws InterruptedException, ExecutionException {
        return mFuture.get();
    }

    /**
     * Waits if necessary for at most the given time for the computation to complete, and then
     * retrieves its result.
     *
     * @param timeout Time to wait before cancelling the operation.
     * @param unit    The time unit for the timeout.
     * @return The computed result.
     * @throws CancellationException If the computation was cancelled.
     * @throws ExecutionException    If the computation threw an exception.
     * @throws InterruptedException  If the current thread was interrupted while waiting.
     * @throws TimeoutException      If the wait timed out.
     */
    public final Result get(long timeout, TimeUnit unit) throws InterruptedException,
            ExecutionException, TimeoutException {
        return mFuture.get(timeout, unit);
    }

    /**
     * Executes the task with the specified parameters. The task returns itself (this) so that the
     * caller can keep a reference to it.
     *
     * <p>Note: this function schedules the task on a queue for a single background thread or pool
     * of
     * threads depending on the platform version.  When first introduced, AsyncTasks were executed
     * serially on a single background thread. Starting with {@link android.os.Build.VERSION_CODES#DONUT},
     * this was changed to a pool of threads allowing multiple tasks to operate in parallel.
     * Starting
     * {@link android.os.Build.VERSION_CODES#HONEYCOMB}, tasks are back to being executed on a
     * single
     * thread to avoid common application errors caused by parallel execution.  If you truly want
     * parallel execution, you can use the {@link #executeOnExecutor} version of this method with
     * {@link #THREAD_POOL_EXECUTOR}; however, see commentary there for warnings on its use.
     *
     * <p>This method must be invoked on the UI thread.
     *
     * @param params The parameters of the task.
     * @return This instance of AsyncTask.
     * @throws IllegalStateException If {@link #getStatus()} returns either {@link
     *                               AsyncTask.Status#RUNNING} or {@link AsyncTask.Status#FINISHED}.
     * @see #executeOnExecutor(java.util.concurrent.Executor, Object[])
     * @see #execute(Runnable)
     */
    public final AsyncTask<Params, Progress, Result> execute(int type, Params... params) {

        if (type == TYPE_NET) {

            return executeOnExecutor(THREAD_POOL_EXECUTOR, params);
        } else {
            return executeOnExecutor(THREAD_POOL_EXECUTOR_LOCAL, params);
        }
    }

    /**
     * Executes the task with the specified parameters. The task returns itself (this) so that the
     * caller can keep a reference to it.
     *
     * <p>This method is typically used with {@link #THREAD_POOL_EXECUTOR} to allow multiple tasks
     * to
     * run in parallel on a pool of threads managed by AsyncTask, however you can also use your own
     * {@link Executor} for custom behavior.
     *
     * <p><em>Warning:</em> Allowing multiple tasks to run in parallel from a thread pool is
     * generally
     * <em>not</em> what one wants, because the order of their operation is not defined.  For
     * example,
     * if these tasks are used to modify any state in common (such as writing a file due to a
     * button
     * click), there are no guarantees on the order of the modifications. Without careful work it
     * is
     * possible in rare cases for the newer version of the data to be over-written by an older one,
     * leading to obscure data loss and stability issues.  Such changes are best executed in
     * serial;
     * to guarantee such work is serialized regardless of platform version you can use this
     * function
     * with {@link #SERIAL_EXECUTOR}.
     *
     * <p>This method must be invoked on the UI thread.
     *
     * @param exec   The executor to use.  {@link #THREAD_POOL_EXECUTOR} is available as a
     *               convenient
     *               process-wide thread pool for tasks that are loosely coupled.
     * @param params The parameters of the task.
     * @return This instance of AsyncTask.
     * @throws IllegalStateException If {@link #getStatus()} returns either {@link
     *                               AsyncTask.Status#RUNNING} or {@link AsyncTask.Status#FINISHED}.
     * @see #execute(Object[])
     */
    public final AsyncTask<Params, Progress, Result> executeOnExecutor(Executor exec,
                                                                       Params... params) {
        if (mStatus != Status.PENDING) {
            switch (mStatus) {
                case RUNNING:
                    throw new IllegalStateException("Cannot execute task:"
                            + " the task is already running.");
                case FINISHED:
                    throw new IllegalStateException("Cannot execute task:"
                            + " the task has already been executed "
                            + "(a task can be executed only once)");
            }
        }

        mStatus = Status.RUNNING;

        onPreExecute();

        mWorker.mParams = params;
        exec.execute(mFuture);

        return this;
    }

    /**
     * This method can be invoked from {@link #doInBackground} to publish updates on the UI thread
     * while the background computation is still running. Each call to this method will trigger the
     * execution of {@link #onProgressUpdate} on the UI thread.
     *
     * {@link #onProgressUpdate} will note be called if the task has been canceled.
     *
     * @param values The progress values to update the UI with.
     * @see #onProgressUpdate
     * @see #doInBackground
     */
    protected final void publishProgress(Progress... values) {
        if (!isCancelled()) {
            sHandler.obtainMessage(MESSAGE_POST_PROGRESS,
                    new AsyncTaskResult<Progress>(this, values)).sendToTarget();
        }
    }

    /**
     * Convenience version of {@link #execute(Object...)} for use with a simple Runnable object.
     * See
     * {@link #execute(Object[])} for more information on the order of execution.
     *
     * @see #execute(Object[])
     * @see #executeOnExecutor(java.util.concurrent.Executor, Object[])
     */
//    public static void execute(Runnable runnable) {
//        sDefaultExecutor.execute(runnable);
//    }
    private void finish(Result result) {
        if (isCancelled()) {
            onCancelled(result);
        } else {
            onPostExecute(result);
        }
        mStatus = Status.FINISHED;
    }

    /**
     * Indicates the current status of the task. Each status will be set only once during the
     * lifetime
     * of a task.
     */
    public enum Status {
        /**
         * Indicates that the task has not been executed yet.
         */
        PENDING,
        /**
         * Indicates that the task is running.
         */
        RUNNING,
        /**
         * Indicates that {@link AsyncTask#onPostExecute} has finished.
         */
        FINISHED,
    }

    private static class InternalHandler extends Handler {
        @SuppressWarnings({"rawtypes", "unchecked"})
        @Override
        public void handleMessage(Message msg) {
            AsyncTaskResult result = (AsyncTaskResult) msg.obj;
            switch (msg.what) {
                case MESSAGE_POST_RESULT:
                    // There is only one result
                    result.mTask.finish(result.mData[0]);
                    break;
                case MESSAGE_POST_PROGRESS:
                    result.mTask.onProgressUpdate(result.mData);
                    break;
            }
        }
    }

    private static abstract class WorkerRunnable<Params, Result> implements Callable<Result> {
        Params[] mParams;
    }

    private static class AsyncTaskResult<Data> {
        final AsyncTask<?, ?, ?> mTask;
        final Data[] mData;

        AsyncTaskResult(AsyncTask<?, ?, ?> task, Data... data) {
            mTask = task;
            mData = data;
        }
    }
}


